Gentlereaders,
Though it is true soup is enjoyed year round, even in mid summer's heat, it's best I think on a chilly Friday evening. To that point I have a really good and really easy recipe or you to try.
How To Make French Onion Soup in the Slow Cooker
When I discovered that you can make caramelized onions in the slow cooker with no stirring and virtually no work, it was only a small step from there to French onion soup. Although I’ve made this bistro favorite the classic, Julia-inspired way, now that I know how to make it in the slow cooker, I’m probably never going back to stovetop!
Here’s a step-by-step recipe for blissfully delicious French onion soup made from start to finish in the slow cooker. Well, right up until the cheesy toast. You still need the oven for that, but with soup this easy, what’s a little broiling at the end?
Here’s how it goes: Throw a few pounds of sliced onions in the slow cooker overnight, or for 12 hours (you can slice them in your food processor if you really want to hurry this along). Cook until dark and jammy; you don’t even need to stir. Pour in some broth and walk away again. Come back at dinnertime, ladle out soup, and broil with cheese and toast.
Perfect French onion soup, absolutely hands-off. This is why slow cookers exist, you guys.
Print Recipe
1048Ratings
I made this!
Cutting board and chef's knife
5-quart or larger slow cooker
Oven-safe soup bowls
Nutrition Note: The nutrition info below does not include the bread and Gruyère for topping the soup.
This post has been updated, originally published February 2015.
Show Nutrition
Here’s a step-by-step recipe for blissfully delicious French onion soup made from start to finish in the slow cooker. Well, right up until the cheesy toast. You still need the oven for that, but with soup this easy, what’s a little broiling at the end?
Why the Slow Cooker Makes the Best French Onion Soup
This is one of those magical recipes that makes you say Oh, can it be so easy? And the answer to that, for once, is yes. Yes it can.Here’s how it goes: Throw a few pounds of sliced onions in the slow cooker overnight, or for 12 hours (you can slice them in your food processor if you really want to hurry this along). Cook until dark and jammy; you don’t even need to stir. Pour in some broth and walk away again. Come back at dinnertime, ladle out soup, and broil with cheese and toast.
Perfect French onion soup, absolutely hands-off. This is why slow cookers exist, you guys.
Key Steps for Slow Cooker French Onion Soup
This is a pretty quick and basic guide to making French onion soup. If you want a little more detail, like some of my favorite flavoring add-ins (star anise, cinnamon, rosemary), my opinions on the right ratio of cheese to soup, and other notes on the classic preparation, visit our main French onion soup tutorial.Print Recipe
1048Ratings
I made this!
How To Make French Onion Soup in the Slow Cooker
Serves6 to 8
Ingredients
- 3 pounds yellow onions, peeled, sliced, and cut into quarter-moons
- 2 tablespoons unsalted butter, melted
- 2 tablespoons olive oil
- 2 teaspoons kosher salt, plus more as needed
- Freshly ground black pepper
- 10 cups reduced-sodium beef broth
- 2 tablespoons balsamic vinegar
- 3 tablespoons brandy (optional)
To Serve
- 4 to 6 toasted baguette slices per bowl
- 1/3 cup grated Gruyère cheese per bowl (1 1/3 to 2 cups total)
- Chopped shallot or fresh onion (optional)
Equipment
Instructions
- Season the onions. Place the onions in a 5-quart or larger slow cooker. Stir in the butter, oil, salt, and a generous amount of pepper.
- Cook on LOW for 12 hours. Cover and cook on the LOW setting overnight until the onions should be dark golden-brown and soft, 12 hours or overnight.
- Add the broth and vinegar. Stir in the broth and vinegar.
- Cook for LOW 6 to 8 hours. Cover and continue cooking on the LOW setting for 6 to 8 hours. This is flexible; as long as your slow cooker holds moisture well (wrap a towel over the lid if quite a lot of steam escapes), you can cook the soup for hours. Longer cooking will only intensify the flavors. Taste and season with more salt and pepper if needed, and stir in the brandy if using.
- Portion the soup into oven-safe bowls. Arrange a rack in the upper third of the oven and heat to 350°F. Ladle the soup and onions into oven-safe soup bowls and place the bowls on a rimmed baking sheet.
- Top with toast and shredded cheese. Top each bowl with a slice of toast and a generous quantity of shredded Gruyère cheese, about 1/3 cup per bowl.
- Bake for 20 to 30 minutes. Bake until the cheese is completely melted, 20 to 30 minutes.
- Broil for 2 to 3 minutes. Turn the oven to broil. Broil until the cheese is bubbling and browned, 2 to 3 minutes. Remove from the oven and let cool for a few minutes. Serve with chopped fresh shallot or onion if desired.
Recipe Notes
Adjusting Consistency & Thickness: When I have made this, the soup has always been just the right consistency. But if yours seems a little thin or watery, you can quickly finish it off on the stovetop by simmering gently in a saucepan for 15 minutes or until the broth has reduced a little.Nutrition Note: The nutrition info below does not include the bread and Gruyère for topping the soup.
This post has been updated, originally published February 2015.
Show Nutrition
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